The present invention relates to the field of keyboard musical instruments, and more particularly to an apparatus and related method for accurately detecting, controlling and recording key movement and velocity.
Generally musical performances can be recorded either for sound through analog audio recordings, or in a digital format such as Musical Instrument Digital Interface (MIDI) which stores the actual notes including velocities and duration of key movements in digital format. The MIDI standard has been around for several years, and is widely adopted by the music industry.
There are many devices on the market which allow the piano/keyboard to record MIDI output from a performance, and to play music recorded in a MIDI format from an external source such as another keyboard, a computer or a MIDI sequencer. Unlike electronic keyboards which have internal sound generators (synthesizers), the piano must create sound by the key""s hammer hitting the string. Thus, the sound can be created by a performer playing the piano keys or by a mechanical/electromechanical method used to actuate the keys.
Player pianos have been around for decades, first starting as strictly mechanical devices and then more recently evolving to electromechanical devices. Music recorded in a MIDI format is often used as the main information to play notes in such pianos and can describe 127 different velocities (actually 128 if you include the xe2x80x9cvelocityxe2x80x9d of the note not playing at all) for each key on the piano keyboard.
When using MIDI, there are several bytes of information that are transmitted every time a key is pressed or released. Generally, when a key is pressed, three bytes are transmitted, including: (1) Note On; (2) Key Number; and (3) Velocity (of that key). Likewise, when a key is released, three additional bytes are transmitted including: (1) Note Off; (2) Key Number; and (3) Velocity (of the key being released).
Unfortunately, these and similar mechanical and electromechanical devices are not as precise as the MIDI levels used to describe a music performance. Ambient conditions such as temperature, humidity, and other environmental factors can cause the performance of these devices to be altered or drift over time. For example, as a solenoid is used throughout a musical performance, its own internal temperature can increase changing its performance characteristics in addition to the noted effect of other ambient conditions. The internal rise in temperature is directly related to the operation of the solenoid in accordance with the music being played, and creates an unsatisfactory result for manufacturers.
The present invention seeks to significantly reduce, if not eliminate, this problem through continuous monitoring of the movement and velocity of the keys being actuated by a musician or mechanical or electromechanical device such as a solenoid for improved recording or for determining and adjusting the key""s velocity if the velocity is not within the specified limits or at the desired MIDI velocity. Internal tables may be used for comparison, and if the key""s movement and/or velocity is unsatisfactory, adjustments may be made. Several comparisons and adjustments can be made before a hammer associated with the actuated key strikes the piano string.
Accordingly, it is a primary object of the present invention to provide a novel and improved device and related method that are particularly adapted to detect, control, and record key movement and velocity in a keyboard musical instrument.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, there is provided an improved device capable of detecting, controlling and recording the movement and velocity of a key of a keyboard musical instrument during a first mode of operation, i.e., recording, or a second mode of operation, i.e., playback. In accordance with the broadest teachings of the present invention, the device and related methods may be applied to digital pianos, electronic keyboards, or other musical devices that are capable of generating sounds by pressing a button or key. However, the description that follows will focus primarily on the invention as it pertains to an acoustic piano.
In general, keyboard key velocities range from very slow (hundreds of milliseconds) to very fast (about 20 milliseconds) and are defined as the time from when the key is first actuated to when the hammer of the key strikes the corresponding string.
A standard piano keyboard has 88 keys and three foot pedals. To accurately monitor the key""s movement and velocity and make adjustments if needed, the device measures and responds to any deviation within a very short duration of time, preferably less than one millisecond. This is due to the fact that the position of the key being monitored can change very fast for a loud/hard note, for example, and any information acquired is old if not quickly acted upon.
In accordance with the present invention, the 88 keys and three pedals of a typical keyboard are monitored using a magnetic sensor, and a digital signal processor (DSP) or microprocessor. As each key moves independently from other keys, the task can be further broken down into small groups of keys that are controlled or monitored by one or more microprocessors, DSPs, or preferable, each DSP operates independently, constantly monitoring the keys within its group for movements and determining the accuracy of the movement or velocity. The number of keys that a processor can control can very depending on the capabilities of the processor including its ability to handle measurements quickly, but it is preferred that the number of keys controlled would be thirty or less for each processor. As such, the number of processors in a piano would start with a minimum of three.
The piano can exist in two modes; playback and record. In playback mode, the keys are driven by an actuator in accordance with an external MIDI player causing the notes on the piano to play by themselves. In record mode, someone is physically actuating the keys and generating the MIDI information based on their performance.
Since the processor controls the keys during playback, it also knows which keys within its groups of keys are not being used. These keys that are not being used can be made available for recording even though other keys are being used in playback. This gives the additional feature of a pianist being able to record on top of a song that is being played back. An example of the utility of this feature is self-recorded duets. Specifically, the second half of a duet can be recorded on top of a first, previously recorded part during its playback. This feature is referred to as xe2x80x9csimultaneous playback and recordingxe2x80x9d later in this document.
An additional feature is the fact that due to the independent monitoring of keys, and specifically the parallel computing nature of the preferred embodiment, typical keyboard scanning errors are significantly reduced if not removed altogether. Most keyboards use serial scanning to determine which keys are being played. Serial scanning entails monitoring each key in a sequential fashion from one key to the next, through all 88 keys. Once completed, scanning resumes from the beginning. In this manner, scanning errors are often introduced into the system. Scanning errors result, for example, when a performer plays a key just after the note has been scanned, and thus the key""s movement is not captured until the key is next scanned, i.e., following the scanning of the other 87 keys. This kind of error can result in the incorrect measurement and recording of MIDI velocities. Although the problem can be somewhat reduced by increasing the scanning rate, the present inventive method of monitoring keys preferably through parallel computing techniques, errors are reduced significantly if not eliminated since each key is continuously monitored for techniques, significantly reduces, if not eliminates, the changes.
Accordingly, several advantages are offered by the present invention, including: (1) improved accuracy in playback mode is achieved since adjustments can be made while the actuator is moving the key towards the string; (2) automatic switching between playback and recording modes; (3) the utilization of both playback and recording modes of operation at the same time based on the dynamic allocation between the two modes as required; (4) precise timing and individualized monitoring analysis of each key movement; (5) continuous monitoring and adjustment/self-calibration of the actuator; (6) protection against damage to a seized or frozen actuator through automatic shut-down; and (7) the if capability to further monitor additional keyboard recording information (Aftertouch) by monitoring the backcheck position of the key after the key has been fully pressed, and issuing an additional signal if additional pressure is exerted on the key during this time.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described the preferred embodiments of this invention, simply by way of illustration of some of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive